For example, various technologies for improving quality of images formed by a video display device including a backlight, such as a liquid crystal display device, have been developed. A technology called local dimming is one of examples of these technologies.
Patent Literature 1 discloses a technology relating to local dimming. Local dimming is a technology which divides a liquid crystal display panel into a plurality of areas, and dims each of light sources disposed in corresponding one of the areas in accordance with brightness of an image formed in the corresponding area of the liquid crystal display panel. This technology can increase contrast of images within one screen. Each of the light sources is constituted by a light emitting diode (LED), for example.